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2,405,650
Patented Ange 13, '
ES PA'll'E urlorrica;
UNITED
" 2,405,050
colts-Fort METALLIC CASTING AND '
-
.comosrrrou FOR SAME
'
'
'
'
Carl E.. Hartwig, Teaneck, and Raymond E.
Roehrenbeok, Lyndlmrst; N. J.,' assignors‘to
Swan-Finch Oil Corporation, New York, 8.1.,
a corporation of New York
No Drawing. Applicatlon'Junel'i, 1944,1115 " "'
Serial No. s‘iassz.
_
- . scams. " (c1.22-'-1ss)
‘This invention ‘relates to cores for metallic '
We have found that if a .su?‘lcient quantity of
this latter material is employed with urea-form
castings, particularly for metals such -as'mag- '
aldehyde‘ resin unpolymerized; say ‘in then to B
.stage, cores made therewith may be removed from
nesium,-aluminum, and other metals having a
melting point below about 1600° F.; ‘and to com-1'
positions for same.
-‘
q
the core boxes substantially without sticking, re-'
sulting in smooth surfaced cores and smooth sur
faced castings. The use of such composition thusv
permits an ‘increase in core production by de
- r -
Core compositions for metal casting consisting
‘ of the well-known linseed oil-kerosene-rosin type
are in general use, but are unsuitable for casting
of magnesium and similar metals becausehcores
creasing the time and labor consumed in cleaning
prepared of such material having sumcient baked 10
strength for handling have too high-hot strength
We havefound also that baked cores made with
causing cracks in magnesium and like castings
our composition have a .much higher resistancev
to moisture than straight urea-formaldehyde
and the burnt core is dimcult to remove. ' Urea
coreboxes.
‘ formaldehyde has been heretofore proposed as a
' core binder for light metal casting. Particularly 15
when cores'of considerable size are made, it is .
necessary to use about 50% of such resin with
- approximately 50% of cereal binder in order. to
‘
Y
.
cores. This, we believe";v is due to the fact that
the calcium magnesium ligno-sulfonate acts to
form a co-polymer with the urea-formaldehyde.
We can not state positively that such co-polymer
is formed, but we do know‘ at the end of the bak
ing period, that a polymerized resin'is obtained
increase the ‘green strength. Such cores are mois
ture absorbent when baked . and thereby, lose 20 which is more resistant to water than the usual
strength and, prior to baking, render the compo-'
sition made therewith somewhat sticky. The
green composition tends to stick to the core boxes,
formaldehyde-urea polymer and attracts sub
stantially no moisture accordingly. Furthermore,
when straight urea-formaldehyde is used for
resulting in poor surface on the cores which is
cores, is is well known that cereal binders are re
re?ected in poor surfaces on the ?nished casting. 25 quired in many of the cores to provide sumcient
green strength for handling prior to baking. By
The principal object of the present invention
is accordingly to provide an improved core for
the use of our composition, a greater green
magnesium and similar metal casting which shall
strength is acquired, thus permitting elimination
produce on baking a polymerized core which has
of cereal binder in many‘ smaller cores where it
substantially no tendency to absorb moisture 30 was previously used with the urea-formaldehyde‘
resins and decreasing the amount of such binder
from the air.
.
Another object is to provide a core composition
where requiredlin larger cores. This is advan
tageous in the molding of light metals such as
which shall eliminate in large part the stickiness
magnesium,‘ etc., because cereal binder does, not
of the compositions using only urea-formalde
hyde and shall produce a core having a higher 35 burn out readily in casting with magnesium or_
green strength than such composition.
similar metal. Thus, the core on burning has too
high a strength causing shrinkage cracks in the
The invention comprises the novel products, the
magnesium or like casting.
‘
speci?c embodiments of which: are described
The proportions of materials for the core com
hereinafter by way of example in accordance
with which we now prefer to practice the inven 40 position which we employ are as follows:
tion.
~
-
Urea-formaldehyde
We have found in accordance with our inven
_
resin, _______ _____-.. About 70% to about 30%
Calcium magnesium
.'
‘
tion that a core comprising sand, urea-formalde
hyde and a suitable proportion of a calcium mag
ligno-sulfonate-,___ About 30% to about 70%
nesi'umligno-sulfonate gives the desired results 45.
The calcium magnesium ligno-sulfonate is one of _
' These materials are mixed dry in the proportion
of about .5%-to about 1.5% with about 98.5% to v
the products obtained from waste sul?te liquor
99.5% sand or similar core forming granular ma
and is sold under the trade name “Goulac” by
terial. The combined materials are employed in \
Robeson Process Company. A typical proximate 50 the usual manner in making up the core by mois
analysis of this Goulac as furnished by Robeson
tening the sand and binder with water and mold
Process Company is as follows:
‘
'
Calcium _ and
magnesium
Per cent
ligno-sul
ing to the desired shape.
The ' cores are then
baked at about 325° F. to 350°~ F. for about 2 hours
or more.
,
.
9. 01
The following are speci?c examples of our in
vention as we now prefer to practice'it. It is to
be understood that the examples are illustrative
' and, that the invention is not to be restricted
rota‘ ...-.......'.--..---.---------.. 100.00
thereto except as indicated in the'appended
60 161811318.
fonates
Total sugar
72. 93
I
m
18. 06
Remainder (probably mixture iron salts,
wood tars, etc.) ____________________ _..
2,405,660
3
4
urea-formaldehyde resin mixed with but not
Emmple 1
chemically combined with a calcium magnesium
Fifteen parts by weight of urea-formaldehyde
ligno-sulfonate in sufficient quantity to reduce
resin, designated as BRU 165170-of the Bakelite
Company, being a partly polymerized resin in the
substantially the stickiness or the core and on '
baking to render it highly resistant to moisture.
A to ‘.8 stage, ocurring as a white powder, are
2. A sand core composition having a predom
mixed with 10 parts of a calcium magnesium
ligno-sulfonate which is a substantially dry sul
?te-lignite evaporate sold as “Goulac.” This dry
powder mixture constitutes the core composition
and is combined in the proportion of about 1%
thereof to 99% of dry sand, which is then mois
tened with water and molded into the desired
inant content of sand and a binder constituting
about .5% to about 1.5% of the solid material of
the core, said binder consisting of about ‘70% to
about 30% of partially polymerized urea-formal
dehyde mixed with but not chemically combined
with about 30% to about 70% of calcium mag
nesium ligno-sulfonate.
shape. Thereafter, the shape is baked at about
‘ 3. A sand core composition having a predom
350° F. for about 2 hours to polymerize the binder.
Example 2
inant content of sand and a binder constituting
about .5% to about 1.5% of the solid material of
the core, said binder consisting of about 60% of
‘7.5 parts by weight of urea-formaldehyde resin
partially polymerized urea-formaldehyde mixed
oi the kind mentioned in Example 1 are mixed
with but not chemically combined with about
with 17.5 parts of a calcium magnesium ligno 20 40% of calcium magnesium ligno-sulfonate.
sulfonate as also described in Example 1. The
4. A binder composition for forming sand cores
dry powder mixture is combined in the propor
in which the sand predominates, said binder
tion of about 1.5% thereof to 98.5% of dry sand
comprising a‘substantially dry partially polymer
which is then moistened with water and molded
ized urea-formaldehyde mixed with but not
chemically combined with a calcium magnesium
into the desired shape. Thereafter, the molded
shape is baked at about 350° F. for about two
hours, causing polymerization of the binder.
The ingredients in the above examples may
have added thereto other well-known ingredients
for the purposes stated below. For example,
there may be added for green strength any one
ligno-sulfonate.
5. A binder composition for forming sand cores
in which the sand predominates, said binder com
prising about 60% to about 40% of a substan
30
hyde mixed with but not chemically combined
with about 40% to about 60% of calcium mag
or the well-known cereal binders. which we be
lieve are prepared from various types of starches,
nesium ‘ligno-sulfonate.
or clays such as bentonite. Small proportions of,
say, up to 3 or 4% of ?y-ash may be added to
in which the sand predominates, said binder com
prising about 60% of a substantially dry partially
polymerized urea-formaldehyde mixed with but
not chemically combined with about 40% of cal
cium magnesium ligno-sulfonate.
tion. Oxidation inhibitors such as sulfur, boric
acid and ?uoride salts may be added.
1. A core composition consisting predominantly
of sand and containing partially polymerized
'
6. A binder composition for forming sand cores
improve the working properties of the composi
We claim:
tially dry partially polymerized urea-formalde
.
40
‘ CARL E. HARTWIG.
RAYMOND E. ROEHRHBECK.